Molding material, process for producing molded article, and molded article

ABSTRACT

There are disclosed a molding material which is used for molding a styrenic polymer and which is capable of affording moldings that are excellent in solvent resistance and mechanical strength even when produced at a molding temperature almost same as that of ordinary atactic polystyrene, namely at a resin temperature of 260° C. or lower, dispensing with a melt kneading step; a process for producing a molding by molding the above molding material, which process enables to shorten molding cycle time and curtail the producton cost; and the moldings produced thereby. The molding material comprises a dry blend of 10 to 95% by weight of a (A) styrenic polymer having atactic configuration and 2 to 90% by weight of a (B) styrenic polymer having a melting point of 250° C. or lower, a weight average molecular weight of at most 200,000 and mainly syndiotactic configuration.

TECHNICAL FIELD

The present invention relates to a molding material comprising a dryblend of a styrenic resin, a process for producing moldings using themolding material and the moldings produced thereby. More particularly,it is concerned with a molding material comprising a dry blend of astyrenic polymer having an atactic configuration and a styrenic polymerhaving a mainly syndiotactic configuration and specific physicalproperties; a process for producing moldings using the molding material;and the moldings produced thereby.

BACKGROUND ART

A styrenic polymer which has an atactic configuration hereinaftersometimes referred to as “atactic polystyrene”) and which is produced byradical polymerization has heretofore been used for a variety ofapplications because of its availability at a low cost. However, theaforesaid atactic polystyrene, which is non-crystalline because of itsatactic configuration in stereostructure, is not necessarilysatisfactory in regard to solvent resistance, thus restricting itsapplicable field as a molding material. A resin composition of theatactic polystyrene and a polyphenylene ether blended therewith isknown, but likewise it is not necessarily satisfactory in regard tosolvent resistance.

In order to improve the solvent resistance, there has been adopted amethod in which styrene is copolymerized with a polar monomer such asacrylonitrile, methacrylates, acrylates, maleic anhydride andmaleimides. However, the copolymer thus obtained has involved suchproblems as random copolymerization ratio being limited, lowproductivity, unfavorable color tone, malodor and difficulty inrecycling by mixing with an other styrenic resin.

It being so, as an alternative for non-crystalline atactic polystyrene,crystalline syndiotactic polystyrene was developed, and further, thereare proposed resin compositions each comprising the syndiotacticpolystyrene and other resin blended there with so as to improve heatresistance thereof {Japanese Patent Application Laid-OpenNos.104818/1987(Showa-62), 257948/1987 (Showa-62),257950/1987(Showa-62), 182344/1989(Heisei-1), etc.}.

Nevertheless, the problems still remain unsolved in that in the case ofproducing a styrenic resin composition by blending the atacticpolystyrene with the syndiotactic polystyrene, it is necessary to carryout melt kneading prior to the production of the composition by moldingin order to sufficiently manifest such physical properties as solventresistance and mechanical strength, and carry out molding working of thecomposition at a temperature higher than a molding working temperatureof a conventional atactic polystyrene, thereby deteriorating the moldingcycle and causing sinks at thick-walled portions.

DISCLOSURE OF THE INVENTION

In such circumstances; an object of the present invention is to providea molding material which is capable of affording moldings that areexcellent in solvent resistance and mechanical strength in the case ofmolding a styrenic polymer, even if molding working is carried out at amolding working temperature of a conventional atactic polystyrene,dispensing with a melt kneading step; a process of producing themoldings which use the aforesaid the molding material, and in which themolding cycle is shortened and the production cost is curtailed.

As a result of investigation accumulated by the present inventors inorder to solve the foregoing problems involved in the prior arts, it hasbeen found that it is made possible to obtain moldings excellent invarious physical properties such as solvent resistance and mechanicalstrength, even if molding is carried out at a molding workingtemperature of a conventional atactic polystyrene, dispensing with amelt kneading step, by blending an atactic polystyrene with asyndiotactic polystyrene endowed with specific physical properties. Thepresent invention has been accomplished by the aforesaid findings andinformation.

That is to say, the present invention is summarized as follows.

{1} A molding material which comprises a dry blend of 10 to 95% byweight of a (A) styrenic polymer having atactic configuration and 2 to90% by weight of a (B) styrenic polymer which has a melting point of250° C. or lower, a weight average molecular weight of at most 200,000and mainly syndiotactic configuration.

{2} The molding material as defined in item {1} in which the styrenicpolymer having mainly syndiotactic configuration as the component (B)has a melting point of 245° C. or lower, and is blended in an amount of5 to 90% by weight.

{3} The molding material as defined in item {1} in which the styrenicpolymer having mainly syndiotactic configuration as the component (B)has an initial relative crystallinity as measured with a differentialscanning calorimeter being at most 60%.

{4} A process for producing a molding which comprises molding themolding material as defined in any of items {1} to {3} at a a resintemperature of 260° C. or lower.

{5} A molding which is produced by the process as defined in item {4}.

THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

The present invention is constituted of a molding material whichcomprises a dry blend of 10 to 95% by weight of a (A) styrenic polymerhaving atactic configuration and 2 to 90% by weight of a (B) styrenicpolymer having a melting point of 250° C. or lower, a weight averagemolecular weight of at most 200,000 and mainly syndiotacticconfiguration.

As the styrenic polymer having atactic configuration as the component(A) to be used in the present invention, use is made of an atacticpolystyrene which is produced by any of solution polymerization, bulkpolymerization, suspension polymerization and bulk-suspensionpolymerization. As a monomer to be used as a starting material for theatactic polystyrene, use is made of an aromatic vinyl compoundrepresented by the general formula (1):

wherein R is independently of one another, is a substituent group havingat least one atom selected from the group consisting of a halogen atom,carbon atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom,selenium atom, silicon atom and tin atom; m is an integer of 1 to 3; andwhen m is plural, each R may be same or different. The atacticpolystyrene may be a copolymer of the forgoing aromatic vinyl monomerand an other vinyl monomer copolymerizable with at least one aromaticvinyl monomer or rubbery polymer. Also, the atactic polystyrene may be ahydride of the polymer or the copolymer, or a mixture thereof.

Examples of the aromatic vinyl compound represented by the generalformula (1) include styrene, α-methylstyrene, methylstyrene,ethylstyrene, isopropylstyrene, tert-butylstyrene, phenylstyrene,vinylstyrene, chlorostyrene, bromostyrene, fluorostyrene,chloromethylstyrene, methoxystyrene and ethoxystyrene. Of these areparticularly preferable styrene, p-methylstyrene, m-methylstyrene,p-tert-butylstyrene, p-chlorostyrene, m-chlorostyrene andp-fluorostyrene. Any of those may be used alone or in combination withat least one other.

Examples of an other vinyl monomer copolymerizable with the aromaticvinyl compound include vinylcyanide compounds such as acrylonitrile andmethacrylonitrile; acrylic esters such as methyl acrylate, ethylacrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexylacrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate,dodecyl acrylate, octadecyl acrylate, phenyl acrylate and benzylacrylate; methacrylic esters such as methyl methacrylate, ethylmethacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate,octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate,dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate andbenzyl methacrylate; and maleimide based compounds such as maleimide,N-methyl maleimide, N-ethyl maleimide, N-butyl maleimide, N-laurylmaleimide, N-cyclohexyl maleimide, N-phenyl maleimide andN-(p-bromophenyl) maleimide.

Examples of rubbery polymers copolymerizable with the aromatic vinylcompound include polybutadiene, styrene-butadiene copolymer,acrylonitrile-butadiene copolymer, diene-based rubber such aspolyisoprene, ethylene-α-olefin copolymer, ethylene-α-olefin-polyenecopolymer, non-diene based rubber such as polyacrylic esters,styrene-butadiene block copolymer, hydrogenated styrene-butadiene blockcopolymer, ethylene-propylene elastomer,styrene-graft-ethylene-propylene elastomer, ethylenic ionomer resin andhydrogenated styrene-isoprene copolymer.

The molecular weight of the atactic polystyrene to be used as theforegoing component (A) is not specifically limited but is generally atleast 10,000, preferably at least 50,000 expressed in terms of weightaverage molecular weight. The atactic polystyrene having a weightaverage molecular weight of less than 10,000 is unfavorable because ofdeteriorated thermal and mechanical properties of the molding producedtherefrom. Likewise, the molecular weight distribution thereof is notspecifically limited in its wideness and narrowness, but variousmolecular weight distributions are applicable thereto.

Moreover, in order to enhance the impact resistance of the moldings tobe produced in the present invention, a rubbery elastomer may be used aspart of and in combination with the component (A) according to thepurpose. Specific examples of usable rubbery elastomer include naturalrubber, polybutadiene, polyisoprene, polyisobutylene, neoprene,polysulfide rubber, thiokol rubber, acrylic rubber, urethane rubber,silicone rubber, epichlorohydrin rubber, styrene-butadiene blockcopolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB,SEBC), styrene-butadiene-styrene block copolymer (SBS) hydrogenatedstyrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene blockcopolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP),styrene-isoprene-styrene block copolymer (SIS), hydrogenatedstyrene-isoprene-styrene block copolymer (SEPS), ethylene-propylenerubber (EPM), ethylene-propylene diene rubber (EPDM), core shell typegranular elastomer such as butadiene-acrylonitrile-styrene-core shellrubber (ABS), methyl methacrylate-butadiene-styrene-core shell rubber(MBS), methyl methacrylate-butyl acrylate-styrene-core shell rubber(MAS), octyl acrylate-butadiene-styrene-core shell rubber (MABS), alkylacrylate-butadiene-acrylonitrile-styrene-core shell rubber (AABS),butadiene-styrene-core shell rubber (SBR), siloxane-containing coreshell rubber typified by methyl methacrylate-butyl acrylate-siloxane andrubber formed by modifying any of the foregoing rubber. Of these areparticularly preferably used SBR, SEB, SEBS, SIR, SEP, SIS, SEPS, coreshell rubber, EPM, EPDM and rubber formed by modifying any of the rubberjust mentioned. Any of the above-exemplified rubbery elastomers may beused alone or in combination with at least one other.

The blending proportion of the rubbery elastomers to be used as part ofthe component (A) is at most 80%, preferably at most 60%, morepreferably at most 50% each by weight, since a blending proportion ofmore than 80% by weight sometimes causes deterioration in solventresistance and modulus of elasticity.

Further, in order to enhance the heat resistance of the molding materialin the present invention, polyphenylene ether may be blended as part ofthe component (A). The polyphenylene ether to be used is preferably anyof those as described in U.S. Pat. Nos. 3,306,874, 3,306,875, 3,257,357and 3,257,358. The aforesaid polyphenylene ether is prepared byoxidation coupling reaction in which a phenolic compound having at leastone substituent group is made into a homopolymer or copolymer in thepresence of a copper amine complex. Preferably usable copper aminecomplex is that derived from a primary amine, a secondary amine or atertiary amine.

Examples of the polyphenylene ether suitable for use as part of thecomponent (A) include poly(2,3-dimethyl-6-ethyl-1,4-phenylene ether),poly(2-methyl-6-chloromethyl-1,4-phenylene ether),poly(2-methyl-6-hydroxyethyl-1,4-phenylene ether),poly(2-methyl-6-n-butyl-1,4-phenylene ether),poly(2-ethyl-6-isopropyl-1,4-phenylene ether),poly(2-ethyl-6-n-propyl-1,4-phenylene ether),poly(2,3,6-trimethyl-1,4-phenylene ether),poly{2-(4′-methylphenyl)-1,4-phenylene ether},poly(2-bromo-6-phenyl-1,4-phenylene ether), poly(2-phenyl-1,4-phenyleneether), poly(2-chloro-1,4-phenylene ether), poly(2-methyl-1,4-phenyleneether), poly(2-chloro-6-ethyl-1,4-phenylene ether),poly(2-chloro-6-bromo-1,4-phenylene ether),poly(2,6-di-n-propyl-1,4-phenylene ether),poly(2-methyl-6-isopropyl-1,4-phenylene ether),poly(2-chloro-6-methyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2,6-dibromo-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenyleneether), poly(2,6-diethyl-1,4-phenylene ether) andpoly(2,6-dimethyl-1,4-phenylene ether). Of these,poly(2,6-dimethyl-1,4-phenylene ether) is particularly preferable.

Moreover, there may be used not only a homopolymer of a phenoliccompound but also a copolymer of two or more thereof. Further, thehomopolymer and copolymer may be modified with a modifying agent such asmaleic anhydride or fumaric acid. Also there may be used a graftcopolymer or block copolymer of an aromatic compound such as styrene andany of the foregoing polyphenylene ether.

The molecular weight as expressed in terms of intrinsic viscosity inchloroform at 25° C. of the polyphenylene ether to be used there ispreferably at most 0.5 deciliter, more preferably at most 0.45deciliter. The reason is that polyphenylene ether having an intrinsicviscosity of more than 0.5 deciliter, when blended therein, sometimesbrings about lowered fluidity of the molding material at the time ofmolding.

The blending proportion of the polyphenylene ether as part of thecomponent (A) is in the range of 5 to 80% by weight, preferably 10 to60% by weight based on the total weight of the component (A). Theblending proportion thereof, when being less than 5% by weight, leads toinsufficient effect on enhancing the heat resistance, whereas theblending proportion thereof, when being more than 80% by weight, sometimes brings about deteriorated fluidity of the molding material at thetime of molding.

Next, the syndiotactic configuration in a styrenic polymer having mainlysyndiotactic configuration means that its stereo-structure is ofsyndiotactic configuration, namely, the stereo-structure in which phenylgroups or substituted phenyl groups as side chains are locatedalternately at opposite direction relative to the main chain consistingof carbon-carbon bonds. In this case, the tacticity is quantitativelydetermined by the nuclear magnetic resonance method (¹³C-NMR method)using carbon isotope. The tacticity as determined by ¹³C-NMR method canbe denoted in terms of proportions of structural units continuouslyconnected to each other, namely, a diad in which two structural unitsare connected to each other, a triad in which three structural units areconnected to each other and a pentad in which five structural units areconnected to each other. The styrenic polymers having such syndiotacticconfiguration as stated in the present invention usually means styrenicpolymers or copolymers each having such a syndiotacticity as determinedby ¹³C-NMR method that the proportion of racemic diad is at least 75%,preferably at least 85%, or the proportion of racemic pentad is at least30%, preferably at least 50%.

Examples of such styrenic polymers or copolymers include polystyrene,poly(alkylstyrene), poly(halogenated styrene), poly(halogenatedalkylstyrene), poly(alkoxystyrene), poly(vinyl benzoate), hydrogenatedpolymers thereof, the mixture thereof, and copolymers containing thepolymers as main components.

Specific examples of the poly(alkylstyrene) include poly(methylstyrene),poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene),poly(phenylstyrene), poly(vinylnaphthalene) and poly(vinylstyrene).Examples of the poly(halogenated styrene) include poly(chlorostyrene),poly(bromostyrene) and poly(fluorostyrene). Examples of thepoly(halogenated alkylstyrene) include poly(chloromethylstyrene).Examples of the poly(alkoxystyrene) include poly(methoxystyrene) andpoly(ethoxystyrene). Of these are particularly preferable polystyrene,poly(p-methylstyrene), poly(m-methylstyrene), poly(tert-butyl-styrene),poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene),hydrogenated polystyrene and the copolymers containing the structuralunits thereof.

In regard to the process for producing the styrenic polymer havingmainly syndiotactic configuration, a well known process is applicablethereto, for instance, a process described in Japanese PatentApplication Laid-Open Nos.187708/1987 (Showa-62), wherein such styrenicpolymer is produced by polymerizing a styrenic monomer in the presenceor absence of a solvent such as an inert hydrocarbon by using a catalystcomprising a titanium compound and a condensation product of water andtrialkylaluminum. In addition, the poly(halogenated alkylstyrene) andthe hydrogenated polymers thereof can be produced by the processdescribed, for instance, in Japanese Patent Application Laid-OpenNos.46912/1989 (Heisei-1) and 178505/1989 (Heisei-1).

The styrenic polymer having mainly syndiotactic configuration to be usedas the component (B) of the molding material according to the presentinvention, which is obtainable in the above-mentioned manner, has amelting point of 245° C. or lower and a weight average molecular weightof at most 200,000. The weight average molecular weight is measured at135° C. by gel permeation method using trichlorobenzene as a solvent.

The use of the polymer as the component (B) having a melting point ofhigher than 250° C. in an attempt to mold the mixture obtained by dryblend with the aforesaid atactic polystyrene as the component (A) at amolding temperature of ordinary atactic polystyrene, brings aboutdeterioration in solvent resistance and mechanical strength due toinsufficient mixing in a cylinder of a molding machine. Thus the polymeras the component (B) has a melting point of preferably 245° C. or lower.

Likewise, the use of the polymer as the component(B) having a weightaverage molecular weight of more than 200,000 in an attempt to mold themixture obtained by dry blend with the aforesaid atactic polystyrene asthe component (A) at a molding temperature of ordinary atacticpolystyrene, brings about deterioration in solvent resistance andmechanical strength due to insufficient mixing in a cylinder of amolding machine.

Moreover, the preferably usable polymer as the component(B) is thathaving an initial relative crystallinity as measured with a differentialscanning calorimeter being at most 60% preferably at most 50%, morepreferably at most 40%. The use of the polymer as the component (B)having an initial relative crystallinity of at most 60% in an attempt tomold the mixture obtained by dry blend with the aforesaid atacticpolystyrene as the component (A) at a molding temperature of ordinaryatactic polystyrene, brings about improvement in melt characteristicsfor the molding material in a cylinder of a molding machine and besides,improvement in solvent resistance and mechanical strength for themoldings obtained, as compared with the polymer as the component (B)having an initial relative crystallinity of more than 60%.

In addition, there may be used the component (B) blended with any ofrubbery components, other resins and additives. Specific examples of therubbery components include diene based rubber such as styrene-butadienecopolymer and acrylonitrile-butadiene copolymer, non-diene based rubbersuch as ethylene-α-olefin copolymer, ethylene-α-olefin-polyene copolymerand polyacrylic ester, styrene-butadiene block copolymer (SB),styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene blockcopolymer (SI), styrene-isoprene-styrene block copolymer (SIS),hydrogenated styrene-butadiene block copolymer (SEB), hydrogenatedstyrene-butadiene-styrene block copolymer (SEBS), ethylene-propyleneelastomer, ethylene-graft-ethylene-propylene elastomer, ethylenicionomer resin, hydrogenated styrene-isoprene block copolymer(SEP) andhydrogenated styrene-isoprene-styrene block copolymer (SEPS). Of theseare particularly preferably used ethylene-α-olefin copolymer, SB, SBS,SI, SIS, SEBS and SEPS. Any of the above-exemplified rubbery elastomersmay be used alone or in combination with at least one other.

With regard to the blending proportion of the atactic polystyrene as thecomponent (A) and the styrenic polymer having mainly syndiotacticconfiguration as the component (B), the blend comprises 10 to 95%,preferably 20 to 95%, more preferably 50 to 85% by weight of thecomponent (A), and 2 to 90% preferably 5 to 90%, more preferably 10 to80%, particularly preferably 15 to 50% by weight of the component (B).When the blending proportion of the component (A) is more than 95% byweight or the blending proportion of the component (B) is less than 2%by weight, the molding obtained by molding the blend of the components(A) and (B) can not sufficiently manifest the effect on enhancingsolvent resistance or mechanical strength of the molding thus obtained.On the other hand, the blending proportion of the component (A) is lessthan 10% by weight or the blending proportion of the component (B) ismore than 90% by weight, the manufacturing cost is made disadvantageous.

The molding material according to the present invention, which comprises10 to 95% by weight of the component (A) and 2 to 90% by weight of thecomponent (B) as a basic constitution, may be blended with a properamount of any of additives that are generally blended in a resincomposition such as nucleating agent, plasticizer, mold release agent,antioxidant, flame retardant, flame retardant aid, dye, pigment andantistatic agent; thermoplastic resin; and rubber. Any of the additive,thermoplastic resin and rubber, when blended with the molding material,may be blended with the component (A) or (B) in advance or may beblended therewith simultaneously with the blending of the components (A)and (B).

The above-mentioned nucleating agent is added for the purpose ofaccelerating the crystallization of the styrenic polymer having mainlysyndiotactic configuration, and enhancing the solvent resistancethereof. Examples of the nucleating agent include a metallic salt of acarboxylic acid such as aluminum di(p-t-butylbenzoate), a metallic saltof phosphoric acid such as methylenebis(2,4-di-butylphenol) sodium acidphosphate, talc and phthalocyanine derivatives, any of which may be usedalone or in combination with at least one other.

Examples of the plasticizer include polyethylene glycol, polyamideoligomer, ethylenebisstearamide, phthalic esters, polystyrene oligomer,polyethylene wax, mineral oil and silicone oil, any of which may be usedalone or in combination with at least one other.

Examples of the mold release agent include polyethylene wax, siliconeoil, long chain carboxylic acids and metal salts of long chaincarboxylic acids, any of which may be used alone or in combination withat least one other.

Examples of the antioxidant include a variety of compounds, from whichwell known compounds of phosphorus base, phenol base or sulfur base maybe arbitrarily selected for use.

Examples of the flame retardant include brominated polymer such asbrominated polystyrene, brominated syndiotactic polystyrene andbrominated polyphenylene ether, brominated aromatic compounds such asbrominated diphenylalkane and brominated diphenyl ether and phosphorusbase flame retardant such as trichlene diphosphate, triphenyl phosphateand tris-3-chloropropyl phosphate, any of which may be selected for use.Examples of the flame retardant aid include antimony compounds such asantimony trioxide. The above-cited flame retardant and the like may beused alone or in combination with at least one other.

Examples of the thermoplastic resins include polyolefinic resins such aslinear high density polyethylene, linear low density polyethylene, highpressure processed low density polyethylene, isotactic polypropylene,syndiotactic polypropylene, block polypropylene, random polypropylene,polybutene, 1,2-polybutadiene, cyclic polyolefin andpoly-4-methylpentene; polystyrenic resins such as polystyrene, impactresistant polystyrene, ABS resin, AS resin and SMA resin; polyesterbased resin such as polycarbonate, polyethylene terephthalate andpolybutylene terephthalate; polyamide based resin such as polyamide 6and polyamide 6,6; polyarylene sulfide, any of which may be used aloneor in combination with at least one other.

The molding material according to the present invention may be producedby compounding both the components (A) and (B), and at need, theabove-mentioned various additives that are properly compounded and dryblending the compounded components. The machinery and equipment to beused for dry blending are not specifically limited, but there are usablea Henschel mixer, a ribbon mixer, a tumble mixer and the like.

The molding material thus obtained by dry blending, without being meltkneaded, can be supplied as such to a molding machine so that it isprocessed into a molding. Accordingly, one step in molding can bedispensed with, whereby the molding process is made economical, thusminimizing the degree of deterioration in the resin componentsaccompanying the heat hysteresis.

The process for producing moldings by using the molding materialaccording to the present invention is not specifically limited, butthere are usable well known processes such as injection molding andextrusion molding. The resin temperature upon molding may be similar toa molding temperature of ordinary atactic polystyrene, and is 260° C. orlower, preferably 250° C. or lower. The molding temperature thereofhigher than 260° C. causes deterioration in the productivity due toprolonged molding cycle and besides, unfavorably increases the sink atthick-walled portions of the molding thus obtained.

The fact that the molding material improved in solvent resistance andmechanical strength by being composed of the atactic polystyrene andsyndiotactic polystyrene of the present invention can be molded ataround a molding temperature of ordinary atactic polystyrene isattributable to the use, as the component (B) of the molding material,of the polystyrene which has mainly syndiotactic configuration, amelting point of 250° C. or lower and a weight average molecular weightof at most 200,000. As opposed to the foregoing, conventional well knownstyrenic resin compositions comprising atactic polystyrene andsyndiotactic polystyrene have suffered from the disadvantage in thatbecause of its melting point higher than 250° C. and a weight averagemolecular weight more than 200,000, the syndiotactic polystyrenerequires a resin temperature upon molding of higher than 260° C.,unfavorably increases the consumption of energy required for heating andcooling, prolongs the molding cycle, lowers productivity and besidesunfavorably increases the sink at thick-walled portions of the moldingthus obtained.

The moldings according to the present invention produced in theabove-mentioned manner are excellent in solvent resistance and chemicalresistance, are improved in mechanical properties such as impactstrength and elongation, and accordingly are well suited for use in avariety of applications in wide range of industrial fields. Examplesthereof as injection molded products include outer parts for automobilessuch as radiator grill, grill, mark, back panel, door mirror, wheel cap,air spoiler and two-wheeled vehicle; inner parts for automobiles such asinstrument panel, meter hood, pillar, glove box, console box, speakerbox and lid; AV equipment such as housing, chassis, cassette case, CDmagazine and remote control case; refrigerator parts such as lining,tray, arm, door cap and handle; vacuum cleaner parts such as housing,handle, pipe and suction port; air conditioner parts such as housing,fan and remote control case; electrical appliances and parts such asfan, ventilation fan, electric cleaner, parts for lighting equipment andbattery case; parts for printer and copying machine such as housing,chassis, ribbon cassette and tray; personal computer parts such ashousing, floppy disc shell and key board; housing, receiving set andmechanical chassis for telephone and communication equipment; generalmachinery and parts such as sewing machine, register, type writer,computer, optical instruments and musical instruments; toy and leisuregoods such as remote control car, block, parts for pin ball machinestand, surfboard and helmet; sanitary products such as stool seat, stoolseat cover, tank and shower; kitchenware such as lunch box, variousvessels and pot; stationary; furniture; parts for building materials andhouse; and industrial structural materials such as pipe and tray.

Examples as extrusion molding products include basic materials forindustry such as film, sheet, pipe and filament.

In the following, the present invention will be described in furtherdetail with reference to comparative examples and working examples,which however shall not limit the present invention thereto.

EXAMPLES 1 TO 22

{1} Selection of the Component (A)

As the atactic polystyrene being the component (A) of the moldingmaterial according to the present invention, four types of styrenicresins and styrenic resin compositions (a-1) to (a-4) were selected asdescribed hereunder:

(a-1) impact resistant styrenic resin (manufactured by IdemitsuPetrochemical Co., Ltd. under the trade name “IT-44”)

(a-2) impact resistant styrenic resin (manufactured by IdemitsuPetrochemical Co., Ltd. under the trade name. “HT-52”)

(a-3) resin composition consisting of 80% by weight of impact resistantstyrenic resin (manufactured by Idemitsu Petrochemical Co., Ltd. underthe trade name “IT-44”) and 20% by weight of polyphenylene oxideresin(manufactured by Mitsubishi Engineering Co., Ltd. under the tradename “YPX-100L”)

(a-4) resin composition consisting of 50% by weight of impact resistantstyrenic resin (manufactured by Idemitsu Petrochemical Co., Ltd. underthe trade name “IT-44”) and 50% by weight of polyphenylene oxideresin(manufactured by Mitsubishi Engineering Co., Ltd. under the tradename “YPX-100L”)

{2} Selection of the Component (B)

As the styrenic polymer having mainly syndiotactic configuration beingthe component (B) of the molding material according to the presentinvention, six types of styrenic resins (b-1) to (b-6) produced by theprocess described in Japanese Patent Application Laid-OpenNo.104818/1987 (Showa-62) were selected as given in Table 1:

TABLE 1 Weight- Molecular Initial Resin average weight Melting relativecompo- molecular distribu- point crystalli- Code sition weight tion (°C.) nity (%) (b-1) St/p-Me* 195,000 2.2 241  60 (12 mol %) (b-2)St/p-Me* 195,000 2.2 241 100 (12 mol %) (b-3) St/p-Me* 180,000 2.5 230 40 (20 mol %) (b-4) St/p-Me* 180,000 2.5 230 100 (20 mol %) (b-5)St/p-Me* 100,000 2.7 228  50 (20 mol %) (b-6) St/p-Me* 100,000 2.7 228100 (20 mol %)

{Remarks} {circle around (1)} *St/p-Me; styrene/p-methylstyrenecopolymer

{circle around (2)} mol % in parenthesis in the column of Resincomposition denotes the content ratio of p-methylstyrene

{circle around (3)} weight average molecular weight and molecular weightdistribution (weight average molecular weight/number average molecularweight) were measured by gel permeation chromatography using1,2,4-trichlorobezene as the solvent at 135° C. expressed in terms ofpolystyrene.

{circle around (4)} melting point was measured using a differentialscanning calorimeter at a temperature raising rate of 20° C./minute fromthe melt peak position.

{circle around (5)} initial relative crystallinity was measured using adifferential scanning calorimeter at a temperature raising rate of 20°C./minute, and was calculated from the following formula:

Initial relative crystallinity (%)={(ΔH _(TM) −ΔH _(TCC))/ΔH _(TM)}×100

where

ΔH_(TCC) (J/g) is absolute value of cold crystallization peak area perunit weight, and

ΔH_(TM) (J/g) is absolute value of melt peak area per unit weight

{3} Preparation of Dry Blend for the Components (A) and (B) and forMolding Therefrom

The foregoing components (A) and (B) at blending proportions as listedin Table 2 were dry blended by the use of a Henschel mixer, and theninjection molded at a mold temperature set to 40° C. to produce Izodtest pieces, tensile test pieces, flexural test pieces and bar type testpieces of 1.6 mm in thickness for evaluating solvent resistance.

{4} Evaluation of Moldability and Mechanical Strength

In Table 2 are given the results of evaluations of the moldability uponinjection molding in the foregoing item {3} in terms of the moldingcycle by comparison in molding cycle between the molding of thecomponent (A) alone and the molding of the components (A) and (B), inwhich the symbol marks shall have the following meanings:

{circle around (1)} moldable in a comparable cooling time; ◯

{circle around (2)} cooling time needs to be prolonged by 1 to 5seconds; Δ

{circle around (3)} cooling time needs to be prolonged by 5 seconds orlonger; ×

In Table 2 are also given the results of evaluations of the sink uponinjection molding in the foregoing item {3} in terms of the sink bycomparison in sink between the molding of the component (A) alone andthe molding of the components (A) and (B), in which the symbol marksshall have the following meanings:

{circle around (1)} comparable by visual observation; ◯

{circle around (2)} somewhat sink is visually observed; Δ

{circle around (3)} clear sink is visually observed; ×

In Table 2 are also given the results of evaluations of the mechanicalstrength for the test pieces prepared in the foregoing item {3}, inwhich the Izod impact strength with notch was measured according toJIS-K 7110, and the tensile strength was measured according to JIS-K7113

TABLE 2-1 No. of Component (A) Component (B) Molding tempera- ExampleCode weight % Code weight % ture (cylinder), ° C.  1 (a-1) 70 (b-1) 30260  2 (a-1) 70 (b-1) 30 250  3 (a-1) 70 (b-1) 30 245  4 (a-1) 90 (b-3)10 245  5 (a-1) 70 (b-3) 30 245  6 (a-1) 50 (b-3) 50 245  7 (a-1) 30(b-3) 70 245  8 (a-1) 70 (b-5) 30 245  9 (a-2) 70 (b-5) 30 245 10 (a-3)70 (b-5) 30 245 11 (a-4) 70 (b-5) 30 245 12 (a-1) 70 (b-5) 30 235 13(a-2) 70 (b-5) 30 235 14 (a-3) 70 (b-5) 30 235 15 (a-4) 70 (b-5) 30 23516 (a-1) 70 (b-2) 30 260 17 (a-1) 70 (b-2) 30 250 18 (a-1) 70 (b-2) 30245 19 (a-1) 70 (b-4) 30 245 20 (a-2) 70 (b-6) 30 245 21 (a-3) 70 (b-6)30 235 22 (a-4) 70 (b-6) 30 235

TABLE 2-2 Mechanical strength No. of Moldability Impact strength TensileExample Molding cycle sink (KJ/m²) elongation (%)  1 Δ Δ 8.6 24  2 ◯ ◯8.5 23  3 ◯ ◯ 8.5 21  4 ◯ ◯ 9.0 25  5 ◯ ◯ 8.9 24  6 ◯ ◯ 8.9 16  7 ◯ ◯7.3 12  8 ◯ ◯ 8.5 23  9 ◯ ◯ 12.0 30 10 ◯ ◯ 10.0 26 11 ◯ ◯ 11.0 28 12 ◯ ◯8.2 21 13 ◯ ◯ 11.0 23 14 ◯ ◯ 10.4 28 15 ◯ ◯ 11.6 30 16 Δ Δ 8.3 21 17 ◯ ◯8.2 20 18 ◯ ◯ 8.0 18 19 ◯ ◯ 8.4 21 20 ◯ ◯ 11.5 26 21 ◯ ◯ 9.6 24 22 ◯ ◯10.5 25

{5} Evaluation of Solvent Resistance

The bar type test piece of 1.6 mm in thickness for evaluating solventresistance was subjected to 0.5% strain. Thereafter a piece of gauzeinto which each of the under-mentioned solvents had been soaked wasplaced on the strain portion of the test piece, covered with a wrapperto prevent the solvent from volatilizing, and then allowed to stand at80° C. for 24 hours. Subsequently visual evaluation was made of the testpiece for change in surface appearance and crack occurrence:

{circle around (1)}: surfactant manufactured by Kao Corporation underthe trade name “Magiclean”

{circle around (2)}: surfactant manufactured by Shin-nichi MedicoCo.,Ltd. under the trade name “JET α for cleaning air conditioners.

{circle around (3)}: gasoline manufactured by Idemitsu Kohsan Co.,Ltd.under the trade name “Idemitsu Superzeous”

{circle around (4)}: plasticizer (dioctyl phthalate) manufactured byTokyo Kasei Co.,Ltd.

{circle around (5)}: machining oil manufactured by Nippon Oil Co.,Ltd.under the trade name “Unisolve EM”

Next, visual observation for change in surface appearance in theevaluation of solvent resistance was based on the following criteria.The results are wholly given in Table 3.

{circle around (1)}: no change at all; ⊚

{circle around (2)}: hardly changed; ◯

{circle around (3)}: occurrence of cloud or microcracks observed onsurface; Δ

{circle around (4)}: occurrence of roughness or cracks observed onsurface; ×

{circle around (5)}: occurrence of dissolution or large cracks observedon surface; 

TABLE 3-1 No. of Component (A) Component (B) Solvent resistance ExampleCode weight % Code weight % surfactant A  1 (a-1) 70 (b-1) 30 ◯  2 (a-1)70 (b-1) 30 ◯  3 (a-1) 70 (b-1) 30 ◯  4 (a-1) 90 (b-3) 10 ◯  5 (a-1) 70(b-3) 30 ◯  6 (a-1) 50 (b-3) 50 ⊚  7 (a-1) 30 (b-3) 70 ⊚  8 (a-1) 70(b-5) 30 ◯  9 (a-2) 70 (b-5) 30 ⊚ 10 (a-3) 70 (b-5) 30 ⊚ 11 (a-4) 70(b-5) 30 ⊚ 12 (a-1) 70 (b-5) 30 ◯ 13 (a-2) 70 (b-5) 30 ◯ 14 (a-3) 70(b-5) 30 ⊚ 15 (a-4) 70 (b-5) 30 ⊚ 16 (a-1) 70 (b-2) 30 ◯ 17 (a-1) 70(b-2) 30 ◯ 18 (a-1) 70 (b-2) 30 ◯ 19 (a-1) 70 (b-4) 30 ◯ 20 (a-2) 70(b-6) 30 ◯ 21 (a-3) 70 (b-6) 30 ⊚ 22 (a-4) 70 (b-6) 30 ⊚

TABLE 3-2 No. of Solvent resistance Example Surfactant B GasolinePlasticizer Machining oil  1 ◯ ◯ ◯ ◯  2 ◯ ◯ ◯ ◯  3 ◯ ◯ ◯ ◯  4 Δ Δ Δ Δ  5◯ ◯ ◯ ◯  6 ◯ ◯ ◯ ◯  7 ◯ ◯ ◯ ◯  8 ◯ ◯ ◯ ◯  9 ◯ ◯ ◯ ◯ 10 ◯ ⊚ ◯ ◯ 11 ◯ ⊚ ◯◯ 12 ◯ ◯ ◯ ◯ 13 ◯ ◯ ◯ ◯ 14 ◯ ⊚ ◯ ◯ 15 ◯ ⊚ ◯ ◯ 16 ◯ ◯ ◯ ◯ 17 ◯ ◯ ◯ ◯ 18 ◯◯ ◯ ◯ 19 ◯ ◯ ◯ ◯ 20 ◯ ◯ ◯ ◯ 21 ◯ ⊚ ◯ ◯ 22 ◯ ⊚ ◯ ◯

Comparative Examples 1 to 22

{7} Selection of the Component (A)

As the atactic polystyrene being the component (A), four types ofstyrenic resins and styrenic resin compositions (a-1) to (a-4) wereselected as is the case with Example 1.

{2} Selection of the Component (B)

Styrenic polymers which had mainly syndiotactic configuration, but whichhad such physical properties that fail to meet the specification of thecomponent (B) according to the present invention were selected in seventypes. In Table 4 are given the seven types of such styrenic resin as(c-1) to (c-7)

TABLE 4 Weight- Molecular Initial Resin average weight Melting relativecompo- molecular distribu- point crystalli- Code sition weight tion (°C.) nity (%) (c-1) Styrenic 150,000 2.4 270 60 homopolymer (c-2)St/p-Me* 250,000 2.3 247 55  (7 mol %) (c-3) St/p-Me* 180,000 2.5 247 53 (7 mol %) (c-4) St/p-Me* 250,000 2.3 242 48 (12 mol %) (c-5) St/p-Me*330,000 2.2 242 40 (12 mol %) (c-6) St/p-Me* 250,000 2.4 230 40 (20 mol%) (c-7) St/p-Me* 350,000 2.2 230 38 (20 mol %)

{3} Preparation of Dry Blend for the Components (A) and (C) and forMolding Therefrom

The foregoing components(A) and (C) at blending proportions as listed inTable 5 were dry blended by the use of a Henschel mixer, and theninjection molded at a mold temperature set to 40° C. to produce testpieces same as in Example 1.

{4} Evaluation of Moldability and Mechanical Strength

Evaluations were made of the moldability and mechanical strength by theuse of each of the test pieces obtained in the preceding item {3} in thesame manner as in Example 1. The results are given in Table 5.

TABLE 5-1 No. of Molding Comp. Component (A) Component (C) temperatureExample Code weight % Code weight % (cylinder), ° C.  1 (a-1) 100  —  0245  2 (a-2) 100  —  0 245  3 (a-3) 100  —  0 245  4 (a-4) 100  —  0 245 5 (a-1) 90 (c-1) 10 245  6 (a-1) 70 (c-1) 30 245  7 (a-1) 50 (c-1) 50245  8 (a-1) 30 (c-1) 70 245  9 (a-1) 70 (c-1) 30 250 10 (a-1) 70 (c-1)30 260 11 (a-1) 70 (c-1) 30 270 12 (a-1) 70 (c-1) 30 280 13 (a-1) 70(c-2) 30 245 14 (a-1) 70 (c-3) 30 245 15 (a-1) 70 (c-4) 30 245 16 (a-1)70 (c-5) 30 245 17 (a-1) 70 (c-6) 30 245 18 (a-1) 70 (c-7) 30 245 19(a-1) 70 (c-7) 30 250 20 (a-1) 70 (c-7) 30 260 21 (a-1) 70 (c-7) 30 27022 (a-1) 70 (c-7) 30 280

TABLE 5-2 No. of Mechanical strength Comp. Moldability Impact strengthTensile Example Molding cycle sink (KJ/m²) elongation (%)  1 ◯ ◯ 9.0 25  2 ◯ ◯ 12.0 30   3 ◯ ◯ 10.8 28   4 ◯ ◯ 12.2 32   5 ◯ ◯ 5.0 4  6 ◯ ◯ 4.32  7 ◯ ◯ 4.0 2  8 ◯ ◯ 3.5 2  9 ◯ ◯ 3.7 2 10 Δ Δ 3.8 3 11 X X 4.0 5 12 XX 7.5 20  13 ◯ ◯ 5.0 3 14 ◯ ◯ 5.5 5 15 ◯ ◯ 6.3 6 16 ◯ ◯ 6.0 5 17 ◯ ◯ 6.97 18 ◯ ◯ 6.5 6 19 ◯ ◯ 7.0 7 20 Δ Δ 7.2 8 21 X X 7.8 15  22 X X 8.0 20 

{5} Evaluation of Solvent Resistance

By the use of the bar type test pieces prepared in the preceding item(3), evaluations were made of solvent resistance of the test pieces inthe same manner as in Example 1. The results are given in Table 6.

TABLE 6-1 No. of Comp. Component (A) Component (B) Solvent resistanceExample Code weight % Code weight % surfactant A  1 (a-1) 100  —  0   2(a-2) 100  —  0 X  3 (a-3) 100  —  0 X  4 (a-4) 100  —  0 X  5 (a-1) 90(c-1) 10 X  6 (a-1) 70 (c-1) 30 X  7 (a-1) 50 (c-1) 50 X  8 (a-1) 30(c-1) 70 X  9 (a-1) 70 (c-1) 30 X 10 (a-1) 70 (c-1) 30 Δ 11 (a-1) 70(c-1) 30 ◯ 12 (a-1) 70 (c-1) 30 ⊚ 13 (a-1) 70 (c-2) 30 X 14 (a-1) 70(c-3) 30 Δ 15 (a-1) 70 (c-4) 30 Δ 16 (a-1) 70 (c-5) 30 Δ 17 (a-1) 70(c-6) 30 ◯ 18 (a-1) 70 (c-7) 30 X 19 (a-1) 70 (c-7) 30 Δ 20 (a-1) 70(c-7) 30 Δ 21 (a-1) 70 (c-7) 30 ◯ 22 (a-1) 70 (c-7) 30 ◯

TABLE 6-2 No. of Comp. Solvent resistance Example Surfactant B GasolinePlasticizer Machining oil  1      2  X    3  X    4  X    5X X X X  6 X X X X  7 X X X X  8 X X X X  9 X X X X 10 X X X X 11 Δ Δ ΔΔ 12 ◯ ◯ ◯ ◯ 13 X X X X 14 X X X X 15 Δ Δ Δ Δ 16 X X X X 17 Δ Δ Δ Δ 18 XX X X 19 Δ Δ Δ Δ 20 Δ Δ Δ Δ 21 ◯ ◯ ◯ ◯ 22 ◯ ◯ ◯ ◯

Evaluations were made of the test pieces prepared in the under-mentionedExamples 23 to 31 and Comparative Examples 23 to 26 by the followingmethods.

{Evaluation Method}

(1) External Appearance

By observing the test pieces, evaluations were made on the basis of thefollowing criteria.

◯: uniform in whole

Δ: somewhat non-uniform

×: non-uniform or unmelted SPS observed

(2) Impact Resistance

Impact resistance with notch was determined in accordance with JIS K7110.

(3) Chemical Resistance

Detergent

(a) Jet α for air conditioner cleaning (manufactured by in Shin-nichiMedico Co.,Ltd.)

(b) antimicrobial air conditioner cleaner (manufactured by King ChemicalCo.,Ltd.)

(c) potent air conditioner cleaner (manufactured by Kimura SoapCo.,Ltd.)

(d) air conditioner cleaning spray (manufactured by Earth SeiyakuCo.,Ltd.)

(e) power bath cleaning spray (manufactured by S.T. Chemical Co.,Ltd.)

(f) Magic Clean (manufactured by Kao Corporation)

Cosmetics

(g) Biore Make Cleaner (manufactured by Kao Corporation)

(h) Sophyna Moist Cleansing (manufactured by Kao Corporation)

(i) Sophyna UV Protector (manufactured by Kao Corporation)

A flexural test piece for evaluating solvent resistance was subjected toannealing at 80° C. for 48 hours and then to 1% strain. Thereafter apiece of gauze into which each of the above mentioned chemicals had beensoaked was placed on the strain portion of the test piece, and thenallowed to stand at room temperature for 24 hours. Subsequently visualevaluation was made of the test piece for surface roughness and/orcracks occurrence on the basis of the following criteria:

⊚: no change at all

◯: slight surface roughness or cracks observed

Δ: surface roughness or cracks observed

×: dissolved or destroyed

{Material Used}

(A) Component (Rubber Modified Styrenic Polymer)

High impact polystyrene (HIPS) manufactured by Idemitsu PetrochemicalCo.,Ltd.

(B) Component (SPS)

In the following, weight average molecular weight and molecular weightdistribution were measured by gel permeation chromatography (GPC) using1,2,4-trichlorobezene as the solvent at 130° C. Melting point wasmeasured using a differential scanning calorimeter at a temperatureraising rate of 20° C./minute from the melt peak position. Each SPS wasproduced by a well known method.

{circle around (1)} SPS1: styrene/p-methylstyrene copolymer(p-methylstyrene content of 14 mol %), weight average molecularweight=180,000, Mw/Mn=2.3, melting point=237° C.

{circle around (2)} SPS2: SPS1/G1651=80/20% by weight G1951: SEBSmanufactured by Shell Chemical Co.,Ltd. under the trade name “KraytonG1651”

{circle around (3)} SPS3: SPS1/ENGAGE 8150/Septon 2104=80/16/4% byweight ENGAGE 8150: ethylene/α-olefin copolymer manufactured by DuPont-Dow Elastomer Corporation Septon 2104: SEPS manufactured by KurarayCo., Ltd.

{circle around (4)} SPS4: weight average molecular weight=300,000,Mw/Mn=2.5, melting point=270° C.

EXAMPLE 23

A mixture which had been prepared by dry mixing 95% by weight of highimpact polystyrene (HIPS) (manufactured by Idemitsu PetrochemicalCo.,Ltd. under the trade name “HT56”) as the the component (A) and 5% byweight of syndiotactic polystyrene (SPS1) as the component (B), wasinjection molded at a resin temperature (molding temperature) of 250° C.and a mold temperature of 60° C. to prepare Izod test pieces andflexural test pieces. By the use of the test pieces thus obtainedobservation and measurement were made of the appearance, Izod impactstrength and chemical resistance in accordance with the above-mentionedprocedures in (1) to (3). The results are given in Table 7.

EXAMPLES 24 TO 31 Comparative Examples 23 to 26

The procedure in Example 23 was repeated to prepare test pieces exceptthat the composition of the components and molding temperature were eachset to the values as given in Table 7. By the use of the test piecesthus obtained observation and measurement were made of the appearance,Izod impact strength and chemical resistance (detergent resistance andsolvent resistance) in accordance with the above-mentioned procedure in(1) to (3). The results are given in Table 7.

TABLE 7-1 No. of Example 23 24 25 26 27 28 29 Composition of Component(A) HIPS (wt. %) 95 80 50 95 80 50 95 (B) SPS1 (wt. %)  5 20 50 (B) SPS2(wt. %)  5 20 50 (B) SPS3 (wt. %)  5 (B) SPS4 (wt. %) Molding 250  250 250  250  250  250  250  Temperature, ° C. Appearance ∘ ∘ ∘ ∘ ∘ ∘ ∘ IzodImpact 10 10  9 10 12 13 10 Strength (KJ/m²) Chemical Resistance (a) Δ ∘⊚ Δ ⊚ ⊚ Δ (b) Δ ∘ ⊚ Δ ⊚ ⊚ Δ (c) Δ ∘ ⊚ Δ ∘ ⊚ Δ (d) Δ ∘ ⊚ Δ ∘ ⊚ Δ (e) Δ ∘⊚ Δ ∘ ⊚ Δ (f) Δ ∘ ∘ Δ ∘ ∘ Δ (g) Δ ∘ ⊚ Δ ⊚ ⊚ Δ (h) Δ ∘ ∘ Δ ∘ ∘ Δ (i) x ΔΔ x Δ ∘ x

TABLE 7-2 No. of Comp. Example 23 24 25 26 Composition of Component (A)HIPS (wt. %) 100  95 80 50 (B) SPS1 (wt. %) (B) SPS2 (wt. %) (B) SPS3(wt. %) (B) SPS4 (wt. %)  5 20 50 Molding Temperature, ° C. 220 250 250 250  Appearance ◯ Δ X X Izod Impact Strength  9  6  4  2 (KJ/m²)Chemical Resistance (a) X X X X (b) X X X X (c) X X X X (d) X X X X (e)X X X X (f) X X X X (g) X X X X (h) X X X X (i) X X X X

As demonstrated in Table 7, when compared with the moldings ofComparative Examples 23 to 26, the moldings of Examples 23 to 31 areexcellent in not only appearance and impact resistance but also inchemical resistance.

INDUSTRIAL APPLICABILITY

According to the molding material of the present invention, it is madepossible not only to immediately supply a molding machine with a dryblend of the molding material as such, dispensing with a melt kneadingstep, but also to carry out molding at a molding temperature almost sameas that of ordinary atactic polystyrene. Consequently, the moldingmaterial enables to shorten the period of time required for molding,thus enhance productivity and besides curtail energy consumptionrequired therefor. Moreover, the moldings produced thereby are excellentin solvent resistance as well as mechanical properties such as impactstrength and tensile elongation.

What is claimed is:
 1. A molding material, comprising a dry blend of 10 to 95% by weight of a (A) styrenic polymer having atactic configuration and 2 to 90% by weight of a (B) styrenic polymer having a melting point of 250° C. or lower, a weight average molecular weight of at most 200,000 and mainly syndiotactic configuration wherein the styrenic polymer having mainly syndiotactic configuration as the component (B) has an initial relative crystallinity as measured with a differential scanning calorimeter being at most 60%.
 2. A process for producing a molding comprising molding a molding material at a resin temperature of 260° C. at the highest, wherein the molding material comprises a dry blend of 10 to 95% by weight of a (A) styrenic polymer having atactic configuration and 2 to 90% by weight of a (B) styrenic polymer having a melting point of 250° C. or lower, a weight average molecular weight of at most 200,000 and mainly syndiotactic configuration and the styrenic polymer having mainly syndiotactic configuration as the component (B) has an initial relative crystallinity as measured with a differential scanning calorimeter being at most 60%.
 3. A molding produced by the process according to claim
 2. 